Carbamate-melamine textile finish

ABSTRACT

Wrinkle-resistant finishes for cellulosic textile materials. More particularly, it relates to aqueous textile finishes containing polymethylol hydroxyethyl carbamate and a methylated, highly methylolated melamine; to the method of applying the finishes to cellulosic textiles; and to the treated textile materials.

United States Patent Roth [451 Apr. 25, 1972 54] CARBAMATE-MELAMINE TEXTILE 3,144,299 8/1964 Frick et al ..8/1 16.3 FINISH 3,369,858 2/1968 Lourigan et al.. 17/1394 X 3,378,397 4/1968 Silvestri et a1. ..l l7/l39.4 [72] Inventor: Philip B. Roth, Brldgewater Township,

Somerset County Primary ExaminerWilliam D Martin [73] Assignee: American Cyanamld Company, Stamford, Assistant Examiner-Theodore G. Davis COYm- Attorney-Charles J. Fickey [22] Filed: Sept. 15, 1969 [57] ABSTRACT [21] App]. No.: 858,151

. Wrinkle-resistant finishes for cellulosic textile materials. More particularly, it relates to aqueous textile finishes containing 2% 5i "117/ [17/1395 b polymethylol hydroxyethyl carbamate and a methylated,- E g 5 43 highly methylolated melamine; to the method of applying the 260/29 R 16 finishes to cellulosic textiles; and to the treated textile materials.

[561 References Cited 5 Claims, No Drawings UNITED STATES PATENTS 2,339,203 1/1944 Stiegler et al. ..1l7/l39.4

CARBAMATE-MELAMINE TEXTILE FINISH This invention relates to wrinkle-resistant finishes for cellulosic textile materials. More particularly, it relates to aqueous textile finishes containing polymethylol hydroxyethyl carbamate and a methylated, highly methylolated melamine; to the method of applying the finishes to cellulosic textiles; and to the treated textile materials.

Aqueous textile finishes containing polymethylolalkyl carbamates are used to impart wash-and-wear and permanent press properties to cellulosic textile materials. Such carbamate compounds have the following formula:

C II ROCN (CHzOH) 2 dimethylol carbamate R is lower alkyl or hydroxyalkyl.

In order to obtain a high degree of methylolation of the lower-alkyl carbamate, i.e. about 1.6-1.8 moles of combined formaldehyde per mole of carbamate, it is necessary to use a large excess of formaldehyde in the reaction of the carbamate with formaldehyde under alkaline conditions. The product, an aqueous solution of polymethylol lower-alkyl carbamate contains a relatively large amount (typically 7-10 percent) of free formaldehyde and can be used as a textile finish without further processing. Cellulosic textile materials treated with this finish demonstrate a high degree of wrinkle recovery and normal losses in tensile strength, with a minimal loss in strength due to chlorine retention. The high free formaldehyde content of this finish is undesirable because the odor of formaldehyde is very obnoxious during the textile finishing operation. Also, special processing'procedures are required to remove the residual free formaldehyde from the treated textile material.

Polymethylol lower-alkyl carbamate finishes have been developed wherein the relatively large amounts of free formaldehyde are reduced by subsequent reaction of the free formaldehyde with melamine and/or urea compounds such as ethyleneurea, or with other reactants capable of reacting with formaldehyde. For example, melamine can be added and reacted with a large proportion of the free formaldehyde, followed by addition of ethyleneurea and reaction with most of the remaining free formaldehyde. By this procedure it is possible to reduce the free formaldehyde to 1.0-2.0percent. These polymethylol carbamate finishes with reduced free formaldehyde provide excellent wrinkle recovery properties with normal losses in tensile strength when applied to cellulosic textile materials. Unfortunately, textiles treated with such finishes suffer from a very high strength loss due to chlorine retention after laundering.

It is therefore an object of this invention to provide a wrinkle recovery finish for cellulosic textile materials which will be relatively non-yellowing and have a relative small loss os strength due to chlorine retention after laundering.

A further object is to provide a polymethylol-alkyl carbamate finish of low free formaldehyde content which may be applied to a cellulosic textile without obnoxious odors, yet provide good permanent press properties to the textile.

These and other objects of the invention will become apparent as the description thereof proceeds.

It has now been discovered that an aqueous textile finish containing polymethylol hydroxyethyl carbamate and methylated, highly methylolated melamine can be applied on a cellulosic textile material and cured thereon by heating with an acid-acting metallic salt catalyst to obtain a high degree of wrinkle recovery with relatively small loss in tensile strength and only a negligible to slight loss in strength due to chlorine retention. The finishes of this invention do not contain the large amount of free formaldehyde formerly employed to prevent excessive strength loss due to chlorine retention. Therefore, these finishes are very satisfactory and desirable for use in finishing operations.

The polymethylol hydroxyethyl carbamate employed in this reaction can be prepared in any conventional manner by reacting in aqueous medium hydroxyethyl carbamate with an excess of formaldehyde (between 2.1 and 2.3 moles, preferably about 2.2 moles, of formaldehyde per mole of carbamate) under alkaline conditions. A base, such as an alkali metal hydroxide, eg sodium hydroxide or potassium hydroxide, or organic bases such as amines, can be used to provide the alkaline conditions. A reaction temperature of 40-60C. is advantageously used. The product, an aqueous solution of polymethylol hydroxyethyl carbamate, will contain between about 4 percent and 12 percent of free formaldehyde. Any suitable method can be employed for removing most of the free formaldehyde. It is particularly convenient to add sufficient melamine to the reaction mixture to react with about 50 percent of the free formaldehyde, calculating that a maximum of four moles of formaldehyde will react with one mole of melamine. This reaction can be carried out at a temperature of 50-75C. under acid conditions. (pl-l about 4.0) Sufficient ethyleneurea is then added to reduce the free formaldehyde content to 1.0-2.5 percent. The reaction of ethyleneurea and formaldehyde can be carried out at a temperature of about 60C. under the same acid conditions. The pH of the resulting solution is then adjusted to 7.0-8.0 with with alkali, and sufficient water is added to obtain a storage-stable solution of preferably about 45 percent solids content, but may range from about 30-50 percent. The aqueous solution contains polymethylol hydroxyethyl carbamate and minor amounts of methylol melamine from at least 1 and up to 4 methylol groups per molecule of melamine and methylol ethyleneurea.

The methylated, highly methylolated melamine should contain an average of at least five methylol groups per molecule of melamine and at least three, and up to six, of the methylol groups should be methylated. It can be prepared by reacting melamine with an excess of formaldehyde under alkaline conditions followed by reaction of the resulting polymethylol melamine with methanol under acid conditions. In a particularly advantageous procedure, melamine and paraformaldehyde (8-l0 moles of formaldehyde per mole of melamine) are reacted at reflux temperature in methanolic solution under alkaline conditions (pl-l 9-10.5), and the resulting highly methylolated melamine, having at least five methylol groups per molecule of melamine, is then reacted with methanol under acid conditions (pH 1.5-2.5) at about 110C. until an almost clear solution is obtained. After the pH is adjusted to 9.5-l0.0, methanol is removed by distillation and water is added to provide a solids content of preferably about 65 percent, but may be from about 45-70 percent. The product has a pH of 7.5-8.0.

As stated above, the aqueous textile finish which is applied to'cellulo'sic textile materials in accordance with the process of this invention contains polymethylol hydroxyethyl carbamate and methylated, highly methylolated melamine, the latter having at least five methylol groups of which at least three are methylated. The finish will have a low formaldehyde content, but may contain very minor amounts of other methylolated melamines, ureas, ethyleneureas, etc. The ratio of polymethylol hydroxyethyl carbamate to methylated, highly methylolated melamine is between 40/60 and /20, preferably between 60/40 and 75/25, on a solids weight basis.

Application of the aqueous textile finish to cellulosic textile materials is carried out according to conventional procedures.- Diluted solutions of the reactant are applied to the textile materials by padding, spraying, dipping or other procedure for impregnating the material, and the treated material is dried and then heated at an elevated temperature to effect a cure of the finish on the textile material.

The textile materials contain cellulose, preferably at least 25 percent of the total fiber content. The cellulosic fibers include cotton, rayon, flax, sisal, and others. The textile materials also include blends of cellulosic fibers with other fibers such as the natural and synthetic fibers, examples of which are polyesters, polyamides, acrylics, wool, silk, etc.

The amount of combined carbamate and melamine reactants applied to the fibers will vary depending on the fiber content of the textile material and on the construction of the material. In general, between 1 percent and 25 percent, preferably between 3 percent and 10 percent, of the combined reactants based on the weight of the textile material is used.

it is advantageous to effect the cure of the finish on the textile material in the presence of an acid-acting catalyst of the metal salt type, such as zinc nitrate or magnesium chloride, and mixtures of metal salts such as a mixture containing a major proportion of magnesium chloride and a minor proportion of aluminum chloride. The preferred catalysts are zinc nitrate and a mixture-of magnesium chloride and aluminum chloride.

. The treated textile material can be dried at any temperature up to the curing temperature. lt is normally convenient to dry the fabric in a suitable oven for a brief period at a temperature between 200 and 250F. The drying time depends on theamount of absorbed moisture in the fabric and may vary from 1 to 5 minutes. The dried textile material is then heated at a still higher temperature to effect the cure of the finish. Temperatures between 250F. and 400F., preferably between 300F and 375F., are normally used. The time required is inversely proportional to the temperature and varies from 0.5 to minutes. For a temperature between 340F and 360F., a

heating period of 1.0 to 2.5 minutes is normally satisfactory. lf

desired, the drying and curing operation can be performed at the same time.

The following specific examples are set forth to illustrate the invention and are not intended to be limitative.

EXAMPLE 1 Preparation of Polymethylol Hydroxyethyl Carbamate A mixture of 290.5 g. of Z-hydroxyethyl carbamate, 413.2 g. of 44 percent aqueous formaldehyde and l l g. of 50 percent aqueous sodium hydroxide was stirred at 50C. for 1 hour. The mixture contained about 7 percent of free formaldehyde. After the pH of the mixture was adjusted to 4.0 with nitric acid, 22.5 g. of melamine was added and'the mixture was heated at 60C. for 1 hour. (Free formaldehyde about 3.5 percent). Ethyleneurea (29.5 g.) was added and the mixture was heated at 60C. for 1 hour. The mixture, with a free formaldehyde content of about 1.75 percent, was cooled at 30C. and the pH was adjusted to about 7.5. Water (420 g.) was added to provide a solids content of 45 percent.

EXAMPLE ll Preparation of Methylated, Highly Methylolated Melamine A mixture of 5,400 g. of methanol, 25 g. of 50% sodium hydroxide, 5,075 g. of paraformaldehyde and 2,160 g. of melamine was heated at the reflux temperature (about 80C.) for 1 hour (pH 9.2l0.0). After addition of 3,390 g. of methanol, the mixture was cooled to 40C. and 270 g. of 70 percent nitric acid was slowly added. The temperature was maintained at 40C. 45C. until an almost clear solution was obtained (about 45 minutes). The pH of the solution was adjusted to about 9.7 with 210 g. of 50% sodium hydroxide, and methanol was removed by distillation in vacuo until a solution temperature of 80C. was obtained. The solution (pH 7.5-8.0) was diluted with 3,100 g. of water to provide a solids content of 65 percent.

EXAMPLE Ill Aqueous pad baths l-9 were prepared with the compositions shown in Table 1. The percentages are on a solids basis.

Reactant A Polymethylol hydroxyethyl carbamate (product of EXAMPLE I).

Reactant B Methylated, highly methylolated melamine (product of EXAMPLE I1).

Catalyst A 92% magnesium chloride plus 8% aluminum chloride.

Catalyst B Zinc nitrate.

Catalyst C Magnesium chloride.

Reactant A- Reactant B Catalyst C Pad Baths l-9 were applied to X 80 cotton percale by a standard padding procedure obtaining an 80 percent wet pickup. The treated fabrics were dried at 225 F. for l minute and were then heated at 350 F. for 1.5 minutes. Fabrics l-9, corresponding to Pad Baths l-9, contained 6.0 percent on the weight of the fabric of total reactants and 0.72 percent of catalyst.

Swatches of the treated and untreated fabric were tested for wrinkle recovery by Test Method AATCC 66-1968 and for tensile strength loss due to chlorine retention by Test Method AATCC 92-1967. The latter test was carried out after six washings of the fabric in a home-style washing machine using water at F., a detergent (Tide") and chlorine bleach. The results are shown in Table 2.

This example shows the high strength loss due to chlorine retention encountered when polymethylol hydroxyethyl carbamate is used along as a textile finish. The example also shows the superiority of zinc nitrate and a mixture of 92% magnesium chloride and 8% aluminum chloride as the curing catalyst.

It is well known that cellulosic textile materials treated with methylol melamine textile finishes are subject to yellowing by chlorine bleaches. For that reason, mixtures with higher percentages of methylated, highly methylolated melamine were not included in the above comparisons. Thus, it is desirable to keep the methylolated melamine component of the mixtures of this invention at a minimum. EXAMPLE IV was run with the purpose of arriving at the optimum amount of methylolated melamine to be used in the mixture.

EXAMPLE lV Aqueous Pad Baths l-6 were prepared with the composition shown in Table 3. The reactants and catalysts are defined in EXAMPLE I.

Pad Baths l-6 were applied to 80 X 80 cotton percale by the procedure of EXAMPLE l. Fabrics l-6, corresponding to Pad Baths l-6, contained 6.0 percent of total reactants and 0.72 percent of catalyst.

Swatches of the treated and untreated fabrics were tested for wrinkle recovery and tensile strength loss due to chlorine retention by the procedures of EXAMPLE III. The results are shown in Table 4.

1. A process for imparting cellulosic textile materials with a wrinkle-resistant finish comprising the steps of:

a. impregnating a cellulosic textile material with an aqueous solution of a highly methylolated melamine, containing an average of at least 5 methylol groups per molecule of melamine and from 3 to 6 methylol groups methylated, a

polymethylol hydroxyethyl carbamate and an acid-acting metal salt catalyst, wherein the methylolated melamine/polymethylol hydroxyethyl carbamate ratio is in the range of from 40/60 to /20; and

b. heating the impregnated cellulosic textile to a temperature sufficient to effect a cure therein, whereby a wrinkleresistant finished cellulosic textile material is produced.

2. A process according to claim 1 wherein the acid-acting metal salt catalyst is selected from the group consisting of zinc nitrate, and a mixture consisting of a major amount of magnesium chloride with a minor amount of aluminum chloride.

3. A process according to claim 1 wherein the methylolated melamine has an average of at least 5 methylol groups per melamine group, at least 3 of which are methylated.

4. A process according to claim 3 wherein the cellulosic textile material is impregnated in an aqueous solution of an acidacting metal salt catalyst, the methylolated melamine and the polymethylol hydroxyethyl carbamate, wherein said solution has a solids content in the range of from 45 percent to 70 percent and a pH in the range of 7.5 to 8.0.

5. A wrinkle-resistant textile prepared according to the process of claim 1 wherein the cellulosic textile is impregnatedwith between 1 and 25 percent by weight of the combined reactants, polymethylol hydroxyethyl carbamate and the highly methylolated melamine, based on the weight of the textile' material impregnated. 

2. A process according to claim 1 wherein the acid-acting metal salt catalyst is selected from the group consisting of zinc nitrate, and a mixture consisting of a major amount of magnesium chloride with a minor amount of aluminum chloride.
 3. A process according to claim 1 wherein the methylolated melamine has an average of at least 5 methylol groups per melamine group, at least 3 of which are methylated.
 4. A process according to claim 3 wherein the cellulosic textile material is impregnated in an aqueous solution of an acid-acting metal salt catalyst, the methylolated melamine and the polymethylol hydroxyethyl carbamate, wherein said solution has a solids content in the range of from 45 percent to 70 percent and a pH in the range of 7.5 to 8.0.
 5. A wrinkle-resistant textile prepared according to the process of claim 1 wherein the cellulosic textile is impregnated with between 1 and 25 percent by weight of the combined reactants, polymethylol hydroxyethyl carbamate and the highly methylolated melamine, based on the weight of the textile material impregnated. 